Nonseizing article of aluminum and method of producing the same



March 6,1928. 1,661,448

' C. TAYLOR NONSEIZING ARTICLE OF ALUMINUM AND METHOD OF PRODUCING THE SAME Filed April 24. 1923 Swwwtoz Cyr/Y c5 763/01. saw/w mumm Patented Mar. 6, 1928.

UNITED STATES CYRIL S. TAYLOR, OF NEW KENSINGTON,

COMPANY OF AMERICA, OF PITTSBURGH, PENNSYLVANIA,

PENNSYLVANIA.

PATENT OFFICE.

PENNSYLVANIA, assIeNon "ro ALUMINUM NONSEIZINO ARTICLE 0! ALUMINUM AND METHOD OF PRODUCING THE SAME.

Application filed April 24, 1928. Serial No. 634,228.

As is well known, the use of two relatively movable parts composed of aluminum has not, ll] general, been practicable when the two parts are in contact under pressure, because of the fact that the ahuninum contacting or bearing surfaces seize each other and thereby prevent subsequent movement. For example, if analuminum or aluminum alloy nut is set up firmly on a bolt of similar metal the two seize and as a result neither can be removed from the other without dam age. Similarl aluminum valves cannot be used successfu ly with aluminunrseats. In short, this tendency to seize. or stick has prevented the use' of aluminum and aluminum alloys in many situations where othercharaetcristies-of such metal would make the same highly adiiantageous.

I have" accordingly been led to devise my present invention, which has for chief object to provide a simple and effective way of preventing seizure of aluminum parts, and to this and other ends the invention consists in the novel features hereinafter described.

The invention is based on the discovery that oxidation of one or'both of the aluminum hearing or contacting surfaces, thereby covering such surface or surfaces with a dense adherent coating com rising or containing aluminum in an oxi ized form, will prevent the contacting surfaces from seizing. This coating may be applied in any convenient and suitable manner, as for example, by treatment with a suitable alkali.

The alkali treatment may be carried out by a simple immersion process, which gives excellent results, particularly in the case of alloys of aluminum, as for example, aluminum-silicon or aluminum-copper alloys. In carrying out my invention by this method the object is immersed ina solution of ammonia, preferably hot and containing about 1 part of concentrated aqua ammonia to 9 7 parts of water by volume. The temperature is preferably maintained between 50 C. and 100 C. for most rapid action; in which case it may require to 1 hour or even longer. If the same solution is used cold a satisfactory coatin may be secured after an immersion of 12 ours or more. The hot solution appears, however, to'give the better coating on substantially pure aluminum, although it is frequently more satisfactory in many ways to use the cold solution with aluminum alloys.

Aluminum bolts and nuts with the threads of one or the other or both coated with aluminum oxid by either of the above methods could not be forced to seize even though lock nuts were used and set up to the limit of the strength of the material.

The invention 'is not confined to bolts nuts, and stop-cocks, but may be employed with advantage wherever aluminum parts movable in contact with each other are used, and hence it is only as specific examples that the devices named are illustrated in the accompanying drawings, in which Fig. 1 shows partly in section a nut, and Fig. 2 a bolt, having their threads covered with a coating comprising aluminum oxid;

Fig. 3 is a side view, partly in section, of a stop-cock of the common type, having a tapered plug covered with a coating comprising aluminum oxid.

In Figs. 1 and 2, the nut 10 and the bolt 11 are made of aluminum or aluminum alloy, but their threads are coated with a hard, dense, adherent coating of aluminum in oxidized form which is'capable of preventing seizure. If the bolt and nut shown are to be used together only one need have the nonseizing coating. In Fig. 3, the valve body, 13, the plug 14, washer 15, and nut 16, are all made of aluminum or aluminum alloy but the plug and washer have non-seizing coatings 17.

The non-seizing layer ma sufi'er wear in time, but in some cases at least I have observed that the wear may be so extensive as to leave large areas bare without developing any sensible tendency to seize.

In the appended claims'the word aluminum is used in a eneric sense, to include aluminum alloys. y bearing surfaces I mean an surfaces in contact with each other, whet er plane or curved.

I am aware that it has been proposed to oxidize the surface of electrical conductors of aluminum in the form of wires and the like, for the purpose of insulating the same when wound in a coil, but such wires or bands never have any relative movement A CORPORATION or when so wound and so far as I am aware unoxidized wires or hands have never been known to seize when coiled with their turns in contact with each other. My invention relates to rigid articles or parts and makes relatively sliding or rubbing motion thereof easy even after they have been firmly pressed together for long periods of time.

It is to be understood that the invention is not limited to the features herein specifically illustrated and described but can be carried out in other ways without departing from its spirit.

I claim- 1. A rigid article of aluminum having a bearing surface comprising aluminum in an oxidized form, adapted to prevent seizure when the article is used with its bearing surface in contact with aluminum.

2. A rigid article of aluminum having a bearing surface provided with a dense, adherent coating comprising aluminum in an oxidized form adapted to prevent seizure when the article is used with its bearing surnature.

CYRIL S. TAYLOR. 

